1. Field of the Invention
The invention relates to a safety system for an aircraft provided with functional devices using primary energy.
2. Description of the Prior Art
In civil and military aircraft, certain functional devices use primary energies. “Primary energy” means energy that does not originate from the general power supply system of the aircraft (supplied as a last resort by the engines of the latter), is but from standalone energy sources specially associated with the functional devices in question.
Amongst the primary energy sources frequently used can be cited those operating by pyrotechnics, by high-pressure compressed gases or by high-power high-frequency electromagnetic energy.
In France, such pyrotechnic-based functional devices are governed by a regulation published under reference number C50.SEC.19561 and by standard No. GAM-DRAM-01.
Such energy sources, when they are used in abnormal conditions, may cause risks to their environment and in particular to the ground personnel.
Examples of functional devices of this type are, for example;
on military aircraft: missile-launchers, missile support pylons, bomb-launchers, decoy launchers, emergency arresting hooks, ejector seats, etc.
and on civil aircraft; escape chutes, self-protection decoy launchers, etc.
To prevent the unintentional activation of these functional devices, it is a known practice to provide them with safety means in order to ensure that, on the ground, the primary energies cannot be triggered unintentionally and to prevent the functional devices being activated. These safety means are always operated manually by ground personnel (particularly in the case of military aircraft) or by cabin personnel (particularly for the escape chutes of civil aircraft).
Usually, these safety means act in two ways: on the one hand by direct action by providing a physical disconnection of the control lines of the primary energy intended to actuate the functional device, and on the other hand by mechanically blocking any movement that might be due to the triggering of the primary energy.
An example of a functional device provided with such a conventional safety means is a pylon under a combat aircraft, this pylon being fitted with an assembly for ejecting a payload and comprising, for example, two pyrotechnic charges. FIGS. 1 and 2 of the appended drawings illustrate this example.
A payload such as a missile (not shown) is designed to be suspended from hooks CR1 and CR2 provided under a pylon P (represented on a support carriage in FIG. 1) attached beneath the wing of an aircraft. The hooks CR1 and CR2 may be opened in flight thanks to the presence of two pyrotechnic charges C1 and C2 positioned respectively in housings forming explosion chambers making it possible to transfer the energy of the gases originating from the explosion to ejection pistons (not visible) and the hooks CR1 and CR2 in order to release the payload.
For the purpose of preventing any undesirable operation on the ground of this functional device, two independent removable safety barriers B1 and B2 are provided one of these barriers B1 consisting of a door designed, in flight, to provide the electric contact allowing the firing of the charges C1 and C2 and, on the ground, by opening it and retaining it in the open position, to physically interrupt the power supply of the system of priming the pyrotechnic charges C1 and C2. The door is opened or closed by the ground personnel usually without the aircraft pilot being able to intervene or perceive the closed or open state.
This first barrier B1 is called “electric safety”. In the open position, the door has an unambiguous visual appearance for the ground personnel with regard to the safe state of the priming system that is associated therewith.
The second barrier B2 consists of a pin making it possible, by its insertion into a housing provided for this purpose, to block all mechanical movement in the functional device, even if the pyrotechnic charges C1 and C2 should be accidentally primed. The barrier or pin B2 is associated with a bright-colored flag (bright orange or red, for example) marker FC making it possible to visually notice its presence. It is also inaccessible to the pilot installed in the cockpit and cannot be observed by the latter.
During the preparation of the aircraft for take-off, the ground personnel or, where necessary, the cabin personnel must render such barriers inoperative by “removing” them in order to arm the functional devices that the aircraft is fitted with and conversely, after the landing of the latter, the same personnel must disarm the functional devices by putting the barriers in place again.
Both military and civil aircraft may be fitted with many primary-energy functional devices. For example, on a military aircraft it is possible routinely to find up to ten or even more, while on a jumbo airliner for example, this number may be even much greater in particular because of the large number of emergency exits that must be fitted with chutes to be armed before take-off and disarmed after landing.
The result of this is a major workload and responsibility for the personnel and a not inconsiderable risk of errors that may cause a potential danger on the ground in the event of a malfunction of a primary energy source (forgetting to put in place a barrier after landing) and in flight a malfunction of a functional device (forgetting to remove a barrier before take-off).